As petroleum exploration and development is preceded, petroleum exploitation becomes more and more difficult. In contrast, a large quantity of petroleum is required as the national economy is developed rapidly. It is an urgent task to speed up petroleum development. At present, the drilling engineering is a domain where fund and technology are cast intensively. In the early stage of oil field development, the cost of the drilling engineering accounts for about 50% of the total cost of the entire petroleum engineering; in the modern oil field development, the cost of the drilling engineering has been reduced to about 30% of the total cost of the drilling engineering by virtue of innovations and advancements in drilling techniques. Therefore, the acceleration of drilling speed has a close relation with petroleum exploration and development as well as final benefit.
Presently, petroleum exploration and development has turned to complex oil-gas reservoirs, and the increasingly complex subsurface geological conditions, especially the discovery and exploitation of shale gas, has put forward extremely high requirements for the drilling engineering. The technical problems encountered by modern drilling engineering become more and more austere. Most oil fields have a present situation of low drilling speed and frequent occurrence of downhole accidents. A large number of new techniques and methods have been used domestically and abroad to improve the rate of penetrate, and some achievements have been made.
The Patent Document No. CN10301117B has disclosed an accelerator for well drilling in oil fields, which is composed of the following components: ethylene glycol: 5˜10%; tributyl phosphate: 5˜10%; Turkey red oil: 5˜15%; fatty alcohol polyoxyethylene ether: 5˜10%, wherein, the number of polyoxyethylene groups in the fatty alcohol polyoxyethylene ether is 4 or 5, the fatty alcohol polyoxyethylene ether is alkylalcohol polyoxyethylene ether with carbon number 8-10; polyglycerol: 10˜20%, wherein, the degree of polymerization of the polyglycerol is 4, 6, or 10; and water, which accounts for the remaining content. The accelerator obtained in this patent is environment friendly and attains lubrication and viscosity reducing effects to a certain degree, but can't efficiently improve the rate of penetrate.
In the drilling engineering, drilling fluids are reputed as the “blood of drilling engineering”. The performance of the drilling fluid has direct influence on the speed of drilling work. Therefore, drilling fluids with high performance plays an important role for improving the rate of penetrate and preventing complex accidents during well drilling. However, the water-based drilling fluids that are used widely at present can't meet the requirement for improving the rate of penetrate, and have some problems in well wall stability; oil-based drilling fluids involve problems related with environmental protection and cost. Hence, it is extremely urgent to develop a water-based drilling fluid that can improve the rate of penetrate and save cost.